My T has mentioned her son a few times, but almost never in relation to my therapy. More like "my son is home alone this afternoon, so if he texts, I need to answer" or things along those lines.

She has only talked about him once or twice in relation to family dynamics that I was talking about. I made some comment about never having any privacy in my family. T, in an effort to point out how dysfunctional that is, made the comment that she doesn't expect her son to share every detail of his life with her (her son is pre-teen, I think). I told her that her son is lucky! She will very infrequently use her own family dynamics as an example to help me see what normal should have been when I was growing up. It doesn't happen often, though.